Question No. 5 and Question No. 15

Lesson#7
Question No. 5
This is question number 5 of excersice 4.3
Q.5. Using slopes, show that the triangle with its vertices A(6, 1), B(2, 7) and C(-6, -7) is a right triangle.
Question No. 15
Q.15. The points A(-1, 2), B(6, 3) and C(2, -4) are vertices of a triangle. Show that the line joining the midpoint D of AB and the midpoint E of AC is parallel to BC and DE=1/2BC.
Introduction to Analytical Geometry
Chapter No 4
Exercise No 4.3
Mathematics
part 2